I agree, Western Digital drives vibrate a lot and have very loud seek noise (even with AAM enabled). Seagates are much quieter, but get very hot during use. The best drives I have found for my Mac Pro are Samsung SP2504Cs, they are quiet, cool and still deliver great performance.I have found the WDs to be louder drives in general (as compared to my Seagate 7200.9 & 7200.10s). I can barely hear the Seagates, but the WD sounds like it is transmitting Morse Code. And if you are running RAID0, well, that's doubling the fun.
Sean